Method for testing piezoelectric/electrostrictive device, testing apparatus, and method for adjusting piezoelectric/electrostrictive device

ABSTRACT

There is provided a method for testing a piezoelectric/electrostrictive actuator, wherein the displacement of a piezoelectric/electrostrictive actuator is estimated on the basis of the relations between one or more frequency characteristic values selected from the group consisting of the heights and areas of the peaks of the resonance waveforms and the difference of the maximum and minimum of the first order or first to higher orders of the resonance frequency characteristic values of the piezoelectric/electrostrictive actuator and the k-th order (k=1 to 4) of the first or first to higher orders of resonance frequencies. According to this piezoelectric/electrostrictive actuator testing method, a piezoelectric/electrostrictive actuator can be tested with high precision without actually driving the same as a product and without being accompanied by any disassembly/breakage.

FIELD OF THE INVENTION

The present invention relates to a method for testing apiezoelectric/electrostrictive device realizing high precision, atesting apparatus, and a method for adjusting apiezoelectric/electrostrictive device.

BACKGROUND ART

In recent years, a displacement control device has been desired foradjusting an optical path length or a position by the submicron infields of optics, precision machinery, semiconductor manufacturing, andthe like. To respond to this, development has been promoted ofpiezoelectric/electrostrictive devices such as apiezoelectric/electrostrictive actuator utilizing strain based on theinverse piezoelectric effect, the electrostrictive effect, or the likecaused when an electric field is applied to a ferroelectric body or anantiferroelectric body and a piezoelectric/electrostrictive sensorutilizing charge generation caused when stress is applied to aferroelectric body/antiferroelectric body on the basis of a similareffect.

For example, an embodiment of a piezoelectric/electrostrictive actuatorhas a structure where a piezoelectric/electrostrictive actuating portionobtained by laminating a lower electrode, apiezoelectric/electrostrictive body, and an upper electrode in sequenceon a surface of a ceramic substrate formed by unitarily forming a thicksupport portion having a cavity and a vibration portion covering thecavity. In such a piezoelectric/electrostrictive actuator, when anelectric field is generated between the upper electrode and the lowerelectrode, a piezoelectric/electrostrictive body of apiezoelectric/electrostrictive material is deformed to generate adisplacement in a vertical direction in the vibration portion. By thefunction of displacing the vibration portion, thepiezoelectric/electrostrictive actuator is applied as an actuatorportion of a precision equipment. Such a piezoelectric/electrostrictiveactuator controls contact or noncontact of a switch or controls fluid asa micro pump by, for example, transforming the vibration portionvertically.

In the case that a piezoelectric/electrostrictive actuator as describedabove is used as an actuator portion or the like of a switch or a micropump, when the displacement is not large enough, a stroke isinsufficient in the switch, and it does not function as a switch, or afluid extrusion amount is insufficient in the micro pump or no fluid canbe extruded in some cases. In addition, for example, in the case ofusing a plurality of piezoelectric/electrostrictive actuators together,when the displacement is varied among the actuators, contact ornoncontact motion becomes unstable, or a fluid extrusion amount becomesunstable to deteriorate quality of the switch or the micro pump.

Therefore, quality control is performed so that the displacement of eachvibration portion may have at least a certain amount and be uniform whenthe same voltage is applied (same electric field is generated).

Incidentally, a prior art document of the same technical field is a WONo. 05/104258 pamphlet.

An example of a testing method performed whenpiezoelectric/electrostrictive actuators are shipped as products is amethod for directly testing the displacement of the vibration portion bythe use of a laser Doppler vibrometer or the like. In addition, therehas been known a method for testing the size and uniformity of thedisplacement when the same voltage is applied (same electric field iscaused) by measuring capacitance of a piezoelectric/electrostrictivebody to be used to resemble a condenser in a manufacturing step of apiezoelectric/electrostrictive actuator.

However, the former method requires high costs when the test isperformed for all the lots of the piezoelectric/electrostrictiveactuators manufactured. In addition, the latter method does not alwayshave high testing precision because the constituents other than thepiezoelectric/electrostrictive actuating portion of thepiezoelectric/electrostrictive actuator are not reflected to the test.

Further, in a recent piezoelectric/electrostrictive actuator, because ofthe advance of miniaturization, slight slippage or variance of the sizemore seriously influences on the properties, and observation of a crosssection with the destruction is necessary to test the slippage orvariance of the size. In such a case, it is impossible to directly testthe products to be shipped.

Such a problem is likewise caused also in apiezoelectric/electrostrictive sensor where the uniform sensorsensitivity is required in the case of the same design andspecification.

SUMMARY OF THE INVENTION

The present invention has been made in view of such problems and aims toprovide a means capable of testing a piezoelectric/electrostrictivedevice (piezoelectric/electrostrictive actuator andpiezoelectric/electrostrictive sensor) highly precisely without actuallydriving the device as a product and without being accompanied by anydisassembly/breakage.

As a result of repeated studies, it was found out that theaforementioned problems can be solved by a means shown below, which leadto the present invention. Specifically, the present invention providesthe following means.

That is, in the first place, according to the present invention, thereis provided a method for testing a piezoelectric/electrostrictiveactuator, wherein the displacement of a piezoelectric/electrostrictiveactuator is estimated on the basis of the relations (α0) between one ormore frequency characteristic values selected from the group consistingof the heights and areas of the peaks of the resonance waveforms and thedifference of the maximum and minimum of the first order or first tohigher orders of the resonance frequency characteristic values of thepiezoelectric/electrostrictive actuator and the k-th order (k=1 to 4) ofthe first or first to higher orders of resonance frequencies.

This relation (α0) can be expressed by, for example, the followingformula (1).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 1} \right\rbrack\mspace{625mu}} & \; \\{{{Estimated}\mspace{14mu}{displacement}\mspace{14mu}{standard}\mspace{14mu}{value}\mspace{14mu}{MV}} = {\sum\limits_{j = 1}^{m}\frac{\sum\limits_{j = m}^{n}{Rj}}{f_{m}^{k}}}} & (1)\end{matrix}$(i=1, 2, 3 . . . m, j=1, 2, 3 . . . n (where n≧m), k=1 to 4)R: resonance frequency characteristic valuesf: resonance frequency

In addition, the aforementioned relation (α0) can be expressed by, forexample, the following formula (2).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 2} \right\rbrack\mspace{625mu}} & \; \\{{{Estimated}\mspace{14mu}{displacement}\mspace{14mu}{standard}\mspace{14mu}{value}\mspace{14mu}{MV}} = {\sum\limits_{i = 1}^{m}\frac{R_{i}}{f_{i}^{k}}}} & (2)\end{matrix}$(i=1, 2, 3 . . . m, k=1 to 4)R: resonance frequency characteristic valuesf: resonance frequency

In a method for testing a piezoelectric/electrostrictive actuator of thepresent invention, it is preferable that the aforementioned relation(α0) is a relation (α1) of dividing the one or more frequencycharacteristic values selected from the group consisting of the heightsand areas of the peaks of the resonance waveforms and the difference ofthe maximum and minimum of the first order of the resonance frequencycharacteristic values of the piezoelectric/electrostrictive actuator bythe k-th order (k=1 to 4) of the first order of resonance frequency toestimate the displacement of the piezoelectric/electrostrictive actuatorby the calculated value obtained by the division.

The relation (α1), which is a subordinate concept of the relation (α0),can be expressed by, for example, the following formula (3). This is thecase of m=1 (only the first term) and n=m (only the first term) in theformula (1).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 3} \right\rbrack\mspace{625mu}} & \; \\{{{Estimated}\mspace{14mu}{displacement}\mspace{14mu}{standard}\mspace{14mu}{value}\mspace{14mu}{MV}} = \frac{R_{1}}{f_{1}^{k}}} & (3)\end{matrix}$

In a method for testing a piezoelectric/electrostrictive actuator of thepresent invention, it is preferable that the aforementioned relation(α0) is a relation (α2) of dividing a sum of the one or more frequencycharacteristic values selected from the group consisting of the heightsand areas of the peaks of the resonance waveforms and the difference ofthe maximum and minimum of the first to higher orders of the resonancefrequency characteristic values of the piezoelectric/electrostrictiveactuator by the k-th order (k=1 to 4) of the first order of resonancefrequency to estimate the displacement of thepiezoelectric/electrostrictive actuator by the calculated value obtainedby the division.

The relation (α2), which is a subordinate concept of the relation (α0),can be expressed by, for example, the following formula (4). This is thecase of m=1 (only the first term) and n=3 in the formula (1).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 4} \right\rbrack\mspace{625mu}} & \; \\{{{Estimated}\mspace{14mu}{displacement}\mspace{14mu}{standard}\mspace{14mu}{value}\mspace{14mu}{MV}} = \frac{R_{1} + R_{2} + R_{3}}{f_{1}^{k}}} & (4)\end{matrix}$

In a method for testing a piezoelectric/electrostrictive actuator of thepresent invention, it is preferable that the aforementioned relation(α0) is a relation (α3) of dividing the one or more frequencycharacteristic values selected from the group consisting of the heightsand areas of the peaks of the resonance waveforms and the difference ofthe maximum and minimum of the resonance frequency characteristic valuefor each of the resonances of the first to higher orders of thepiezoelectric/electrostrictive actuator by the k-th order (k=1 to 4) ofresonance frequency and obtaining the sum of the values for each of theresonances to estimate the displacement of thepiezoelectric/electrostrictive actuator by the calculated value obtainedby the sum.

The relation (α3) which is a subordinate concept of the relation (α0)can be expressed by, for example, the following formula (5). This is thecase of m=3 in the formula (2).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 5} \right\rbrack\mspace{625mu}} & \; \\{{{Estimated}\mspace{14mu}{displacement}\mspace{14mu}{standard}\mspace{14mu}{value}\mspace{14mu}{MV}} = {\frac{R_{1}}{f_{1}^{k}} + \frac{R_{2}}{f_{2}^{k}} + \frac{R_{3}}{f_{3}^{k}}}} & (5)\end{matrix}$

In a method for testing a piezoelectric/electrostrictive actuator of thepresent invention, it is preferable that the displacement of thepiezoelectric/electrostrictive actuator is estimated by a value obtainedby further multiplying any of the aforementioned calculated values bythe capacitance of the piezoelectric/electrostrictive actuator.

Next, according to the present invention, there is provided an apparatusfor testing piezoelectric/electrostrictive actuator, wherein theapparatus is provided with a means for estimating the displacement ofthe piezoelectric/electrostrictive actuator on the basis of therelations (α0) between one or more frequency characteristic valuesselected from the group consisting of the heights and areas of the peaksof the resonance waveforms and the difference of the maximum and minimumof the first order or first to higher orders of the resonance frequencycharacteristic values of the piezoelectric/electrostrictive actuator andthe k-th order (k=1 to 4) of the first or first to higher orders ofresonance frequencies. The aforementioned means can be realized by, forexample, a computer and a software. That is, a testing apparatus of apiezoelectric/electrostrictive actuator of the present invention is acomputer with a program for estimating the displacement of thepiezoelectric/electrostrictive actuator on the basis of the relations(α0) between one or more frequency characteristic values selected fromthe group consisting of the heights and areas of the peaks of theresonance waveforms and the difference of the maximum and minimum of thefirst order or first to higher orders of the resonance frequencycharacteristic values of the piezoelectric/electrostrictive actuator andthe k-th order (k=1 to 4) of the first or first to higher orders ofresonance frequencies. Since the first order or first to higher ordersof the resonance frequency characteristic values and the first order orfirst to higher orders of resonance frequencies can be measured by thenetwork analyzer described later or the like, a testing apparatus for apiezoelectric/electrostrictive actuator of the present invention can beconstituted of, for example, a network analyzer and the aforementionedcomputer with the program, and a method for testing apiezoelectric/electrostrictive actuator of the present invention can beperformed by a testing apparatus for a piezoelectric/electrostrictiveactuator of the present invention.

In an apparatus for testing a piezoelectric/electrostrictive actuator ofthe present invention, it is preferable that the aforementioned relation(α0) is a relation (α1) of dividing the one or more frequencycharacteristic values selected from the group consisting of the heightsand areas of the peaks of the resonance waveforms and the difference ofthe maximum and minimum of the first order of the resonance frequencycharacteristic values of the piezoelectric/electrostrictive actuator bythe k-th order (k=1 to 4) of the first order of resonance frequency andthat the apparatus is provided with a means for estimating thedisplacement of the piezoelectric/electrostrictive actuator by thecalculated value obtained by the division. Such a means can be realizedby a computer and a software.

In an apparatus for testing a piezoelectric/electrostrictive actuator ofthe present invention, it is preferable that the aforementioned relation(α0) is a relation (α2) of dividing a sum of the one or more frequencycharacteristic values selected from the group consisting of the heightsand areas of the peaks of the resonance waveforms and the difference ofthe maximum and minimum of the first to higher orders of the resonancefrequency characteristic values of the piezoelectric/electrostrictiveactuator by the k-th order (k=1 to 4) of the first order of resonancefrequency and that the apparatus is provided with a means for estimatingthe displacement of the piezoelectric/electrostrictive actuator by thecalculated value obtained by the division. Such a means can be realizedby a computer and a software.

In an apparatus for testing a piezoelectric/electrostrictive actuator ofthe present invention, it is preferable that the aforementioned relation(α0) is a relation (α3) of dividing the one or more frequencycharacteristic values selected from the group consisting of the heightsand areas of the peaks of the resonance waveforms and the difference ofthe maximum and minimum of the resonance frequency characteristic valuefor each of the resonances of the first to higher orders of thepiezoelectric/electrostrictive actuator by the k-th order (k=1 to 4) ofresonance frequency and obtaining the sum of the values for each of theresonances and that the apparatus is provided with a means forestimating the displacement of the piezoelectric/electrostrictiveactuator by the calculated value obtained by the sum. Such a means canbe realized by a computer and a software.

In an apparatus for testing a piezoelectric/electrostrictive actuator ofthe present invention, it is preferable that the apparatus is providedwith a means for estimating the displacement of thepiezoelectric/electrostrictive actuator by a value obtained by furthermultiplying the calculated value by the capacitance of thepiezoelectric/electrostrictive actuator. Such a means can be realized bya computer and a software.

Next, according to the present invention, there is provided a method fortesting a piezoelectric/electrostrictive sensor, wherein the detectionsensitivity of a piezoelectric/electrostrictive sensor is estimated onthe basis of the relations (α10) between one or more frequencycharacteristic values selected from the group consisting of the heightsand areas of the peaks of the resonance waveforms and the difference ofthe maximum and minimum of the first order or first to higher orders ofthe resonance frequency characteristic values of thepiezoelectric/electrostrictive sensor and the k-th order (k=1 to 4) ofthe first or first to higher orders of resonance frequencies.

The relation (α10) can be expressed by, for example, the followingformula (6).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 6} \right\rbrack\mspace{625mu}} & \; \\{{{Estimated}\mspace{14mu}{detection}\mspace{14mu}{sensitivity}\mspace{14mu}{standard}\mspace{14mu}{value}\mspace{14mu}{ST}} = {\sum\limits_{i = 1}^{m}\frac{\sum\limits_{j = m}^{n}{Rj}}{f_{m}^{k}}}} & (6)\end{matrix}$(i=1, 2, 3 . . . m, j=1, 2, 3 . . . n (where n≧m), k=1 to 4)R: resonance frequency characteristic valuesf: resonance frequency

In addition, the aforementioned relation (α10) can be expressed by, forexample, the following formula (7).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 7} \right\rbrack\mspace{625mu}} & \; \\{{{Estimated}\mspace{14mu}{detection}\mspace{14mu}{sensitivity}\mspace{14mu}{standard}\mspace{14mu}{value}\mspace{14mu}{ST}} = {\sum\limits_{i = 1}^{m}\frac{R_{i}}{f_{i}^{k}}}} & (7)\end{matrix}$(i=1, 2, 3 . . . m, k=1 to 4)R: resonance frequency characteristic valuesf: resonance frequency

In a method for testing a piezoelectric/electrostrictive sensor of thepresent invention, it is preferable that the relation (α10) is arelation (α11) of dividing the one or more frequency characteristicvalues selected from the group consisting of the heights and areas ofthe peaks of the resonance waveforms and the difference of the maximumand minimum of the first order of the resonance frequency characteristicvalues of the piezoelectric/electrostrictive sensor by the k-th order(k=1 to 4) of the first order of resonance frequency to estimate thedetection sensitivity of the piezoelectric/electrostrictive sensor bythe calculated value obtained by the division.

The relation (α11), which is a subordinate concept of the relation(α10), can be expressed by, for example, the following formula (8). Thisis the case of m=1 (only the first term) and n=m (only the first term)in the formula (6).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 8} \right\rbrack\mspace{625mu}} & \; \\{{{Estimated}\mspace{14mu}{detection}\mspace{14mu}{sensitivity}\mspace{14mu}{standard}\mspace{14mu}{value}\mspace{14mu}{ST}} = \frac{R_{1}}{f_{1}^{k}}} & (8)\end{matrix}$

In a method for testing a piezoelectric/electrostrictive sensor of thepresent invention, it is preferable that the relation (α10) is arelation (α12) of dividing a sum of the one or more frequencycharacteristic values selected from the group consisting of the heightsand areas of the peaks of the resonance waveforms and the difference ofthe maximum and minimum of the first to higher orders of the resonancefrequency characteristic values of the piezoelectric/electrostrictivesensor by the k-th order (k=1 to 4) of the first order of resonancefrequency to estimate the detection sensitivity of thepiezoelectric/electrostrictive sensor by the calculated value obtainedby the division.

The relation (α12), which is a subordinate concept of the relation(α10), can be expressed by, for example, the following formula (9). Thisis the case of m=1 (only the first term) and n=3 in the formula (6).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 9} \right\rbrack\mspace{625mu}} & \; \\{{{Estimated}\mspace{14mu}{detection}\mspace{14mu}{sensitivity}\mspace{14mu}{standard}\mspace{14mu}{value}\mspace{14mu}{ST}} = \frac{R_{1} + R_{2} + R_{3}}{f_{1}^{k}}} & (9)\end{matrix}$

In a method for testing a piezoelectric/electrostrictive sensor of thepresent invention, it is preferable that the relation (α10) is arelation (α13) of dividing the one or more frequency characteristicvalues selected from the group consisting of the heights and areas ofthe peaks of the resonance waveforms and the difference of the maximumand minimum of the resonance frequency characteristic value for each ofthe resonances of the first to higher orders of thepiezoelectric/electrostrictive sensor by the k-th order (k=1 to 4) ofresonance frequency and obtaining the sum of the values for each of theresonances to estimate the detection sensitivity of thepiezoelectric/electrostrictive sensor by the calculated value obtainedby the sum.

The relation (α13), which is a subordinate concept of the relation(α10), can be expressed by, for example, the following formula (10).This is the case of m=3 in the formula (7).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{20mu} 10} \right\rbrack\mspace{596mu}} & \; \\{{{Estimated}\mspace{14mu}{detection}\mspace{14mu}{sensitivity}\mspace{14mu}{standard}\mspace{14mu}{value}\mspace{14mu}{ST}} = {\frac{R_{1}}{f_{1}^{k}} + \frac{R_{2}}{f_{2}^{k}} + \frac{R_{3}}{f_{3}^{k}}}} & (10)\end{matrix}$

In a method for testing a piezoelectric/electrostrictive sensor of thepresent invention, it is preferable that the detection sensitivity ofthe piezoelectric/electrostrictive sensor is estimated by a valueobtained by further multiplying any of the aforementioned calculatedvalues by the capacitance of the piezoelectric/electrostrictive sensor.

Next, according to the present invention, there is provided an apparatusfor testing a piezoelectric/electrostrictive sensor, provided with ameans for estimating the detection sensitivity of apiezoelectric/electrostrictive sensor on the basis of the relations(α10) between one or more frequency characteristic values selected fromthe group consisting of the heights and areas of the peaks of theresonance waveforms and the difference of the maximum and minimum of thefirst order or first to higher orders of the resonance frequencycharacteristic values of the piezoelectric/electrostrictive sensor andthe k-th order (k=1 to 4) of the first or first to higher orders ofresonance frequencies. The aforementioned means can be realized by, forexample, a computer and a software. That is, a testing apparatus of apiezoelectric/electrostrictive sensor of the present invention is acomputer with a program for estimating the detection sensitivity of thepiezoelectric/electrostrictive sensor on the basis of the relations(α10) between one or more frequency characteristic values selected fromthe group consisting of the heights and areas of the peaks of theresonance waveforms and the difference of the maximum and minimum of thefirst order or first to higher orders of the resonance frequencycharacteristic values of the piezoelectric/electrostrictive sensor andthe k-th order (k=1 to 4) of the first or first to higher orders ofresonance frequencies. Since the first order or first to higher ordersof the resonance frequency characteristic values and the first order orfirst to higher orders of resonance frequencies can be measured by thenetwork analyzer described later or the like, a testing apparatus for apiezoelectric/electrostrictive sensor of the present invention can beconstituted of, for example, a network analyzer and the aforementionedcomputer with the program, and a method for testing apiezoelectric/electrostrictive sensor of the present invention can beperformed by a testing apparatus for a piezoelectric/electrostrictivesensor of the present invention.

In an apparatus for testing a piezoelectric/electrostrictive sensor ofthe present invention, it is preferable that the relation (α10) is arelation (α11) of dividing the one or more frequency characteristicvalues selected from the group consisting of the heights and areas ofthe peaks of the resonance waveforms and the difference of the maximumand minimum of the first order of the resonance frequency characteristicvalues of the piezoelectric/electrostrictive sensor by the k-th order(k=1 to 4) of the first order of resonance frequency and that theapparatus is provided with a means for estimating the detectionsensitivity of the piezoelectric/electrostrictive sensor by thecalculated value obtained by the division. Such a means can be realizedby a computer and a software.

In an apparatus for testing a piezoelectric/electrostrictive sensor ofthe present invention, it is preferable that the aforementioned relation(α10) is a relation (α12) of dividing a sum of the one or more frequencycharacteristic values selected from the group consisting of the heightsand areas of the peaks of the resonance waveforms and the difference ofthe maximum and minimum of the first to higher orders of the resonancefrequency characteristic values of the piezoelectric/electrostrictivesensor by the k-th order (k=1 to 4) of the first order of resonancefrequency and that the apparatus is provided with a means for estimatingthe detection sensitivity of the piezoelectric/electrostrictive sensorby the calculated value obtained by the division. Such a means can berealized by a computer and a software.

In an apparatus for testing a piezoelectric/electrostrictive sensor ofthe present invention, it is preferable that the aforementioned relation(α10) is a relation (α13) of dividing the one or more frequencycharacteristic values selected from the group consisting of the heightsand areas of the peaks of the resonance waveforms and the difference ofthe maximum and minimum of the resonance frequency characteristic valuefor each of the resonances of the first to higher orders of thepiezoelectric/electrostrictive sensor by the k-th order (k=1 to 4) ofresonance frequency and obtaining the sum of the values for each of theresonances and that the apparatus is provided with a means forestimating the detection sensitivity of thepiezoelectric/electrostrictive sensor by the calculated value obtainedby the sum. Such a means can be realized by a computer and a software.

In an apparatus for testing a piezoelectric/electrostrictive sensor ofthe present invention, it is preferable that the apparatus is providedwith a means for estimating the detection sensitivity of thepiezoelectric/electrostrictive sensor by a value obtained by furthermultiplying the calculated value by the capacitance of thepiezoelectric/electrostrictive sensor. Such a means can be realized by acomputer and a software.

In the present specification, piezoelectric/electrostrictive actuatorsand piezoelectric/electrostrictive sensors are collectively referred toas piezoelectric/electrostrictive devices. In addition, both the methodfor inspecting a piezoelectric/electrostrictive actuator and the methodfor inspecting a piezoelectric/electrostrictive sensor may be referredto as methods for inspecting piezoelectric/electrostrictive devices.Both the apparatus for inspecting a piezoelectric/electrostrictiveactuator and the apparatus for inspecting apiezoelectric/electrostrictive sensor may be referred to as apparatusesfor inspecting piezoelectric/electrostrictive devices. All of them maybe referred to as inspection methods and inspection apparatuses forpiezoelectric/electrostrictive devices of the present invention.

The resonance frequency and the resonance frequency characteristic valueused in a method and an apparatus for testing apiezoelectric/electrostrictive device of the present invention is aresonance frequency and a resonance frequency characteristic value of anelectrical constant of impedance, admittance (conductance, susceptance),or the like. The resonance frequency and the resonance frequencycharacteristic value can be measured at a high speed at low costs by theuse of a network analyzer or an impedance analyzer. The (first to higherorders of) the resonance frequency characteristic value used in a methodor an apparatus for testing a piezoelectric/electrostrictive device ofthe present invention is at least one (resonance) frequencycharacteristic value selected from the group consisting of the heightsof the peaks of the resonance waveforms (of the first to higher orders),areas (of the resonance waveforms of the first to higher orders), andthe difference of the maximum and minimum (of the resonance waveforms ofthe first to higher orders), and these heights of the peaks, areas, anddifference of the maximum and minimum can be obtained by a chart withfrequency as an axis of abscissas and with, for example, conductance (orimpedance, susceptance, or the like) as an axis of ordinate. The chartcan be obtained by the aforementioned network analyzer or impedanceanalyzer.

In a method and an apparatus for testing apiezoelectric/electrostrictive actuator of the present invention, withregard to a piezoelectric/electrostrictive actuator having apiezoelectric/electrostrictive body and two or more electrodes as theconstituents, since the displacement of a piezoelectric/electrostrictiveactuator is estimated not by using only the capacitance loaded on thepiezoelectric/electrostrictive body as a part of thepiezoelectric/electrostrictive actuator, but estimated on the basis ofthe relations between one or more frequency characteristic valuesselected from the group consisting of the heights and areas of the peaksof the resonance waveforms and the difference of the maximum and minimumof the first order or first to higher orders of the resonance frequencycharacteristic values of the entire piezoelectric/electrostrictiveactuator and the k-th order (k=1 to 4) of the first or first to higherorders of resonance frequencies, the test can be performed with highprecision without relying on experiences. In addition, because of anondestructive test, more precise good or bad decision can be performedquickly. Therefore, error of shipping undesirable products can beinhibited.

In a method and an apparatus for testing apiezoelectric/electrostrictive sensor of the present invention, withregard to a piezoelectric/electrostrictive sensor having apiezoelectric/electrostrictive body and two or more electrodes as theconstituents, since the detection sensitivity of apiezoelectric/electrostrictive sensor is estimated not by using only thecapacitance loaded on the piezoelectric/electrostrictive body as a partof the piezoelectric/electrostrictive sensor, but estimated on the basisof the relations between one or more frequency characteristic valuesselected from the group consisting of the heights and areas of the peaksof the resonance waveforms and the difference of the maximum and minimumof the first order or first to higher orders of the resonance frequencycharacteristic values of the entire piezoelectric/electrostrictivesensor and the k-th order (k=1 to 4) of the first or first to higherorders of resonance frequencies, the test can be performed with highprecision without relying on experiences. In addition, because of anondestructive test, more precise good or bad decision can be performedquickly. Therefore, error of shipping undesirable products can beinhibited.

Next, according to the present invention, there is provided a method foradjusting a piezoelectric/electrostrictive actuator, comprising:

-   -   estimating the displacements of a plurality of        piezoelectric/electrostrictive actuators by the use of a method        for testing any one of the aforementioned        piezoelectric/electrostrictive actuators, and trimming an upper        electrode with regard to at least some of the plurality of        actuators to adjust the displacement of the        piezoelectric/electrostrictive actuators uniformly. By thus        trimming the upper electrode, it is possible to adjust also the        generation force of the piezoelectric/electrostrictive actuator.

In a method for adjusting a piezoelectric/electrostrictive actuator ofthe present invention, it is preferable that the trimming is performedby a processing method by laser irradiation, electron beam irradiation,cutting, or the like. In particular, a processing method by laserirradiation is suitably used because a beam wavelength can be selectedin accordance with characteristics of the material to be removed.

In a method for adjusting a piezoelectric/electrostrictive actuator ofthe present invention, since the trimming forms at least onepredetermined pattern in the vicinity of the central portion of theupper electrode where the maximum displacement is generated, it ispossible to obtain the change of the displacement by a small trimmingamount. As the predetermined pattern used here, a circular through-hole(cross section perpendicular to the axial direction), a slit, or thelike can be considered. In particular, in the processing method by laserirradiation, since the processing shape is easily obtained stably to beable to enhance resolution of a removal area, a circular through-hole issuitably employed. In addition, since resolution of the removal area canbe enhanced effectively by the smaller number of trimming patterns, whenthe pattern is a circular through-hole, the through-hole preferably hasa different diameter. Further, when the aforementioned pattern is aslit, the slit preferably has a different width.

In a method for adjusting a piezoelectric/electrostrictive actuator ofthe present invention, it is preferable that the displacements of aplurality of piezoelectric/electrostrictive actuators is estimated bythe use of a method for testing any of the aforementionedpiezoelectric/electrostrictive actuator and that apiezoelectric/electrostrictive body is trimmed with regard to at leastsome of the plurality of piezoelectric/electrostrictive actuators toadjust the displacement of the piezoelectric/electrostrictive actuatorsuniformly. By trimming the piezoelectric/electrostrictive body, it ispossible to adjust mechanical rigidity of thepiezoelectric/electrostrictive actuator. That is, since the displacementcan be adjusted without changing an electric constant such ascapacitance or equivalent parallel resistance of thepiezoelectric/electrostrictive actuator, it is possible to suppress theadjustment amount on the driving circuit side of thepiezoelectric/electrostrictive actuator to the minimum.

In a method for adjusting a piezoelectric/electrostrictive actuator ofthe present invention, it is preferable that both thepiezoelectric/electrostrictive body and the upper electrode are trimmedwith regard to at least some of the plurality ofpiezoelectric/electrostrictive actuators. Since the generation force andthe mechanical rigidity of the piezoelectric/electrostrictive actuatorcan simultaneously be adjusted by trimming both thepiezoelectric/electrostrictive body and the upper electrode, it ispossible to adjust the displacement of thepiezoelectric/electrostrictive actuator on a grand scale.

In a method for adjusting a piezoelectric/electrostrictive actuator ofthe present invention, it is preferable that the trimming is performedin at least a portion where the maximum displacement of thepiezoelectric/electrostrictive actuator is generated. This enables toadjust the displacement efficiently with a small trimming amount ortrimming area.

In a method for adjusting a piezoelectric/electrostrictive actuator ofthe present invention, it is preferable that the trimming is performedin a portion (the vicinity of the so called side) having the maximumamplitude in the first order of the resonance mode. This makes theprobability of inducing another vibration mode low, and a vibration modesimilar to that of a piezoelectric/electrostrictive actuator withouttrimming can be realized. As a result, it becomes possible to adjust thedisplacement where the change in the first or higher orders of theresonance frequency is suppressed to the minimum.

Next, according to the present invention, there is provided apiezoelectric/electrostrictive actuator obtained by adjusting thedisplacement uniformly by using the aforementioned method for adjustinga piezoelectric/electrostrictive actuator.

Next, according to the present invention, it is preferable that thedetection sensitivity of the plurality of piezoelectric/electrostrictivesensors is estimated by the use of any of the aforementioned methods fortesting a piezoelectric/electrostrictive sensor and that the upperelectrode of each of at least some of the plurality ofpiezoelectric/electrostrictive sensors is trimmed to adjust thedetection sensitivity of the plurality of piezoelectric/electrostrictivesensors uniformly. By thus trimming the upper electrode, it is possibleto adjust the generation force upon driving thepiezoelectric/electrostrictive sensor, and it is possible to adjust thedisplacement upon driving the piezoelectric/electrostrictive sensor.Therefore, it becomes possible to adjust the detection sensitivity ofthe piezoelectric/electrostrictive sensor.

The detection sensitivity of a piezoelectric/electrostrictive sensor inthe present specification means the performance of thepiezoelectric/electrostrictive sensor and a ratio of output to input.For example, when the piezoelectric/electrostrictive sensor is aviscosity sensor for a fluid, the electric charge generation caused whenthe fluid applies stress to the piezoelectric/electrostrictive sensorcan be detected, and the ratio of the electric charge generation amountto the viscosity is the detection sensitivity in this case. By adjustingthe displacement upon driving the fluid sensor, it becomes possible tomake the volume and speed of the fluid to be activated uniform, therebyreducing the measurement error.

In a method for adjusting a piezoelectric/electrostrictive sensor of thepresent invention, it is preferable that the trimming is performed by aprocessing method by laser irradiation, electron beam irradiation,cutting, or the like. In particular, a processing method by laserirradiation is suitably used because a beam wavelength can be selectedin accordance with characteristics of the material to be removed.

In a method for adjusting a piezoelectric/electrostrictive sensor of thepresent invention, since the trimming forms at least one predeterminedpattern in the vicinity of the central portion of the upper electrodewhere the maximum displacement is generated, it is possible to obtain alarge change of detention voltage by a small trimming amount. As thepredetermined pattern used here, a circular through-hole (cross sectionperpendicular to the axial direction), a slit, or the like can beconsidered. In particular, in the processing method by laserirradiation, since the processing shape is easily obtained stably to beable to enhance resolution of a removal area, a circular through-hole issuitably employed. In addition, since resolution of the removal area canbe enhanced effectively by the smaller number of trimming patterns, whenthe pattern is a circular through-hole, the through-hole preferably hasa different diameter. Further, when the aforementioned pattern is aslit, the slit preferably has a different width.

In a method for adjusting a piezoelectric/electrostrictive sensor of thepresent invention, it is preferable that the detective sensitivity of aplurality of piezoelectric/electrostrictive sensors is estimated by theuse of any of the aforementioned methods for testing apiezoelectric/electrostrictive sensor and that apiezoelectric/electrostrictive body is trimmed with regard to at leastsome of the plurality of piezoelectric/electrostrictive sensors on thebasis of the estimated detection sensitivity of each of thepiezoelectric/electrostrictive sensors to adjust the detectionsensitivity of the piezoelectric/electrostrictive sensors uniformly. Bythus trimming the piezoelectric/electrostrictive body, it is possible toadjust mechanical rigidity of the piezoelectric/electrostrictive sensor.Therefore, it is possible to adjust the displacement upon driving thepiezoelectric/electrostrictive sensor, and it is possible to adjust thedetection sensitivity of the piezoelectric/electrostrictive sensor. Thatis, since the detection sensitivity upon driving thepiezoelectric/electrostrictive sensor can be adjusted without changingan electric constant such as capacitance or equivalent parallelresistance of the piezoelectric/electrostrictive sensor, it is possibleto suppress the adjustment amount on the driving circuit side of thepiezoelectric/electrostrictive sensor to the minimum.

In a method for adjusting a piezoelectric/electrostrictive sensor of thepresent invention, it is preferable that thepiezoelectric/electrostrictive body and the upper electrode are trimmedwith regard to at least some of the plurality ofpiezoelectric/electrostrictive sensors. Since the generation force andthe mechanical rigidity of the piezoelectric/electrostrictive sensor cansimultaneously be adjusted by trimming both thepiezoelectric/electrostrictive body and the upper electrode, it ispossible to adjust the detection sensitivity of thepiezoelectric/electrostrictive sensor on a grand scale.

In a method for adjusting a piezoelectric/electrostrictive sensor of thepresent invention, it is preferable that the trimming is performed in atleast a portion where the maximum displacement of thepiezoelectric/electrostrictive sensor is generated. Since this enablesto adjust the generation force and mechanical rigidity upon driving thepiezoelectric/electrostrictive sensor efficiently with a small trimmingamount or trimming area, as a result, it is possible to adjust thedetection sensitivity of the piezoelectric/electrostrictive sensorefficiently.

In a method for adjusting a piezoelectric/electrostrictive sensor of thepresent invention, it is preferable that the trimming is performed in aportion having the maximum amplitude in the first order of the resonancemode. This makes the probability of inducing another vibration mode, anda vibration mode similar to that of a piezoelectric/electrostrictiveactuator without trimming can be realized. As a result, it becomespossible to adjust the detection sensitivity with suppressing the changein the first or higher orders of the resonance frequency to the minimum.

Next, according to the present invention, there is provided apiezoelectric/electrostrictive sensor obtained by adjusting thedetection sensitivity uniformly by using the aforementioned method foradjusting a piezoelectric/electrostrictive sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing an example of a piezoelectric/electrostrictiveactuator and perspective view showing the vibration portion and thesupport portion separately.

FIG. 2 is a cross-sectional view showing the A-A′ cross sectionincluding the vibration portion and piezoelectric/electrostrictiveactuating portion of the piezoelectric/electrostrictive actuator shownin FIG. 1.

FIG. 3 is a cross-sectional view showing the B-B′ cross sectionincluding the vibration portion and the piezoelectric/electrostrictiveactuating portion of the piezoelectric/electrostrictive actuator shownin FIG. 1.

FIG. 4 is a cross-sectional view showing an example of apiezoelectric/electrostrictive actuator where the substrate and thepiezoelectric/electrostrictive actuating portion are shifted from eachother and view showing a cross section corresponding with FIG. 3.

FIG. 5 is a cross-sectional view showing apiezoelectric/electrostrictive actuator where the vibration portion hasa downward undulation (in the figure) and view showing a cross sectioncorresponding with FIG. 3.

FIG. 6A is a cross-sectional view showing an example where apiezoelectric/electrostrictive actuator was applied as an actuatorportion of a micro switch, showing a nonconductive state (off).

FIG. 6B is a cross-sectional view showing an example where apiezoelectric/electrostrictive actuator was applied as an actuatorportion of a micro switch, showing a conductive state (on).

FIG. 7 is a cross-sectional view showing an example of thepiezoelectric/electrostrictive actuator.

FIG. 8 is a cross-sectional view showing an example of thepiezoelectric/electrostrictive actuator.

FIG. 9 is a cross-sectional view showing an example of thepiezoelectric/electrostrictive actuator.

FIG. 10 is a configuration diagram showing an example of a resonancefrequency characteristic value measurement apparatus.

FIG. 11 is a configuration diagram showing an example of a displacementmeasurement apparatus.

FIG. 12 is a configuration diagram showing an example of a frequencycharacteristic measurement system.

FIG. 13 is a graph showing an example of a frequency characteristic of apiezoelectric/electrostrictive actuator.

FIG. 14 is a graph showing a relation between the measured displacementand the capacitance of a piezoelectric/electrostrictive actuator.

FIG. 15 is a graph showing the estimated displacement and the measureddisplacement of a piezoelectric/electrostrictive actuator.

FIG. 16 is a graph showing the relation between the displacement and theestimated displacement standard value MV of apiezoelectric/electrostrictive actuator.

FIG. 17 is a graph showing the relation between the estimateddisplacement and the measured displacement of apiezoelectric/electrostrictive actuator.

FIG. 18A is a schematic view showing a cross section including thevibration portion and the piezoelectric/electrostrictive actuatingportion of a piezoelectric/electrostrictive actuator of the presentinvention adjusted according to a method for adjusting apiezoelectric/electrostrictive actuator of the present invention.

FIG. 18B is a plan view schematically showing apiezoelectric/electrostrictive actuator of the present inventionaccording to the present invention adjusted by a method for adjusting apiezoelectric/electrostrictive actuator of the present invention.

FIG. 19A is a graph showing a displacement in each position in thelongitudinal direction of a piezoelectric/electrostrictive actuator.

FIG. 19B is a graph showing a displacement in each position in theshort-side direction of a piezoelectric/electrostrictive actuator.

FIG. 20 is a plan view schematically showing apiezoelectric/electrostrictive actuator of the present inventionadjusted by a method for adjusting a piezoelectric/electrostrictiveactuator of the present invention.

FIG. 21 is a plan view schematically showing apiezoelectric/electrostrictive actuator of the present inventionadjusted by a method for adjusting a piezoelectric/electrostrictiveactuator of the present invention.

FIG. 22 is a plan view schematically showing apiezoelectric/electrostrictive actuator of the present inventionadjusted by a method for adjusting a piezoelectric/electrostrictiveactuator of the present invention.

FIG. 23 is a plan view schematically showing apiezoelectric/electrostrictive actuator of the present inventionadjusted by a method for adjusting a piezoelectric/electrostrictiveactuator of the present invention.

DESCRIPTION OF REFERENCE NUMERALS USED IN THE DRAWING FIGURES

20, 30, 40, 50, 60, 70, 80, 90: piezoelectric/electrostrictive actuator;44: Substrate; 46: cavity; 66: vibration portion; 68: support portion;73: intermediate electrode; 75: upper electrode; 77: lower electrode;78: piezoelectric/electrostrictive actuating portion 79:piezoelectric/electrostrictive body; 81, 84, 85, 86: circularthrough-hole (through-hole of upper electrode); 82, 87, 88, 89: slit(slit of upper electrode); 83: slit (slit ofpiezoelectric/electrostrictive body); 120: micro switch; 121: terminalboard; and 122: LCR meter.

DETAILED DESCRIPTION OF THE INVENTION

Hereinbelow, embodiments of the present invention will be described withsuitably referring to drawings. However, the present invention shouldnot be construed with limiting to these, and various changes,modifications, and improvements may be made on the basis of knowledge ofa person of ordinary skill in the art as long as they do not deviatefrom the scope of the present invention. For example, though thedrawings show preferable embodiments of the present invention, thepresent invention is not limited by the modes or information shown inthe drawings. When the present invention is carried out or investigated,the means which is the same as or equivalent to the means described inthe present specification can be applied. However, a suitable means isthe means described below.

In the first place, a piezoelectric/electrostrictive actuator capable ofserving as a target of the method and apparatus for testing apiezoelectric/electrostrictive actuator of the present invention. FIGS.1, 2, 3, 4 and 5 are views each showing an example of apiezoelectric/electrostrictive actuator. FIG. 1 is a perspective viewwhere the vibration portion 66 and the support portion 68 are separated,FIG. 2 is a cross-sectional view showing the A-A′ cross sectionincluding the vibration portion 66 and piezoelectric/electrostrictiveactuating portion 78 of the piezoelectric/electrostrictive actuatorshown in FIG. 1, and FIG. 3 is a cross-sectional view showing the B-B′cross section likewise. The piezoelectric/electrostrictive actuator 20in the figure has a substrate 44 and a piezoelectric/electrostrictiveactuating portion 78. The substrate 44 is obtained by unitarily forminga thick support portion 68 having a cavity 46 and a vibration portion 66covering the cavity 46. The piezoelectric/electrostrictive actuatingportion 78 has a piezoelectric/electrostrictive body 79, the upperelectrode 75 formed on one surface, and the lower electrode 77 formed onthe other surface and is disposed on one surface of the substrate 44 insuch a manner that lower electrode 77 contacts the vibration portion 66.

In the piezoelectric/electrostrictive actuator 20, when an electricfield is generated between the upper electrode 75 and the lowerelectrode 77, the displacement is generated in thepiezoelectric/electrostrictive body 79 of apiezoelectric/electrostrictive material to transform the vibrationportion 66. By this function, the piezoelectric/electrostrictiveactuator 20 is applied as an actuator portion for, for example, aprecision equipment.

FIGS. 6A and 6B are cross-sectional views each showing an example wherea piezoelectric/electrostrictive actuator is applied as an actuatorportion for a micro switch. In the micro switch 120 shown in thefigures, a switch electrode 18 is provided inside the cavity 46 of thepiezoelectric/electrostrictive actuator 20, a terminal board 121 isprovided so as to cover the cavity 46, and a switch electrode 19 isprovided so as to face the switch electrode 18. When the vibrationportion 66 is not transformed, the switches 18, 19 are nonconductive(off) (see FIG. 6A). However, when the piezoelectric/electrostrictivebody 79 has a displacement to transform the vibration portion 66, theswitches 18, 19 become conductive (ON) (see FIG. 6B).

As piezoelectric/electrostrictive actuators, besides thepiezoelectric/electrostrictive actuator 20 having one layer of thepiezoelectric/electrostrictive body, piezoelectric/electrostrictiveactuators 70, 30 and 40, whose cross sections are shown in FIGS. 7, 8and 9, are shown as examples. FIG. 7 is a cross-sectional view showing across section according to FIG. 2. FIGS. 8 and 9 are cross-sectionalviews each showing a cross section according to FIG. 3. Each of thepiezoelectric/electrostrictive actuators 70, 30 and 40 shown in FIGS. 7,8 and 9 is in common with the piezoelectric/electrostrictive actuator 20in that it has a substrate 44 and a piezoelectric/electrostrictiveactuating portion 78 and that the substrate 44 is obtained by unitarilyforming a thick support portion 68 having a cavity 46 and a vibrationportion 66 covering the cavity 46. However, each of thepiezoelectric/electrostrictive actuator 70 and thepiezoelectric/electrostrictive actuator 30 (see FIGS. 7 and 8) isdifferent from the piezoelectric/electrostrictive actuator 20 in that ithas two layers of piezoelectric/electrostrictive bodies 79 sandwichedbetween the upper electrode 75 and intermediate electrode 73 and betweenthe intermediate electrode 73 and the lower electrode 77. Thepiezoelectric/electrostrictive actuator 40 (see FIG. 9) is differentfrom the piezoelectric/electrostrictive actuator 20 in that it has threelayers of piezoelectric/electrostrictive bodies 79. In the presentspecification, for convenience sake, the electrode present nearest tothe vibration portion of the piezoelectric/electrostrictive actuatingportion is referred to as the lower electrode, the electrode presentfarthest from the vibration portion is referred to as the upperelectrode, and the electrode other than the upper electrode and thelower electrode is referred to as an intermediate electrode in the casethat a plurality of piezoelectric/electrostrictive bodies are laminated.

Next, with employing the case of the piezoelectric/electrostrictiveactuator 20 as an example, a method for manufacturing apiezoelectric/electrostrictive actuator will be described. In the caseof using a ceramic material for the substrate in manufacturing apiezoelectric/electrostrictive actuator, it can be manufactured by agreen sheet lamination method, and the piezoelectric/electrostrictiveactuating portion can be manufactured by a thin or thick film formationmethod.

The substrate 44 is manufactured as follows. For example, a binder, asolvent, a dispersant, a plasticizer, and the like are added to aceramic powder of, for example, zirconium oxide, and they are mixed toprepare slurry. After the slurry is subjected to a defoaming treatment,a green sheet having a predetermined thickness is manufactured by amethod such as a reverse roll coater method or a doctor blade method.Then, the green sheet is machined by a method such as punching using adie or laser processing into various shapes required. After a pluralityof green sheets are piled up in sequence, a ceramic green laminate bodyis obtained by, for example, pressure bonding with heat. The green sheetlaminate body obtained is fired at a temperature of about 1200 to 1600°C. to obtain the substrate 44.

Next, a piezoelectric/electrostrictive actuating portion 78 is formed onone surface of the substrate 44. For example, the lower electrode 77 isprinted in a predetermined position on the surface of the substrate 44by a membrane formation method such as screen printing, followed byfiring at a temperature of about 1250 to 1450° C., and then thepiezoelectric/electrostrictive body 79 is printed, followed by firing ata temperature of about 1100 to 1350° C., and then the upper electrode 75is printed, followed by firing at a temperature of preferably 500° C. to900° C. to form a piezoelectric/electrostrictive actuating portion 78.Then, an electrode lead for connecting the electrode to the drivingcircuit is printed, followed by firing. By selecting a suitablematerial, unitary firing at one time is also possible after each of theelectrodes of the piezoelectric/electrostrictive actuating portion, thepiezoelectric/electrostrictive body, and the electrode lead are printedsequentially.

After the piezoelectric/electrostrictive actuator 20 is formed asdescribed above, when polarization is required for thepiezoelectric/electrostrictive actuator 20, a polarization treatment isperformed. Polarization is performed by, for example, applying a voltage(polarization voltage) sufficiently higher than the driving voltageexpected to be used between the upper electrode 75 and the lowerelectrode 77. Though it is not limited, when the driving voltage is 30V,polarization is performed by setting the polarization voltage to beabout 70V. Then, the piezoelectric/electrostrictive actuator 20subjected to the polarization treatment is tested to confirm whether thesubstrate 44 and the piezoelectric/electrostrictive actuating portion 78are normally manufactured or not. When the substrate 44 and thepiezoelectric/electrostrictive actuating portion 78 are shifted fromeach other or when the vibration portion 66 has undulation, there is acase that a desired displacement amount cannot be obtained even the same(driving) voltage is applied between the electrodes.

An example of a piezoelectric/electrostrictive actuator has beendescribed above. A piezoelectric/electrostrictive sensor targeted by amethod and an apparatus for testing a piezoelectric/electrostrictivesensor of the present invention has only a difference in theelectrode/mechanical conversion and the mechanical/electrode conversion,and the structure is similar to the aforementionedpiezoelectric/electrostrictive actuator. Regarding thepiezoelectric/electrostrictive sensor, the description with referring toa drawing is omitted.

Next, an apparatus for measuring the resonance frequency characteristicvalue, the displacement, and the capacitance will be described. Theresonance frequency characteristic value and the capacitance are used toestimate the displacement in a method and an apparatus for testing apiezoelectric/electrostrictive actuator of the present invention.

FIG. 10 is a configuration diagram of an apparatus for measuring aresonance frequency characteristic value of apiezoelectric/electrostrictive actuator. The resonance frequencycharacteristic value of a piezoelectric/electrostrictive actuator can bemeasured by electrically connecting the network analyzer 101 to (forexample) the piezoelectric/electrostrictive actuator 20 (see FIGS. 1 to3) to be tested by means of the directional coupler 102 and the prove(measurement jig) to analyze a transmission wave or a reflection wave tothe input signal (reflection method or the like), for example, by theconductance and susceptance.

FIG. 11 is a configuration diagram of an apparatus for measuring adisplacement when a piezoelectric/electrostrictive actuator is driven.The displacement of the piezoelectric/electrostrictive actuator 20 canbe measured by a waveform measurement analysis apparatus 114 by (forexample) vibrating the piezoelectric/electrostrictive actuator 20 (seeFIGS. 1 to 3) to be tested by a drive voltage signal output from thedrive apparatus 111 having a signal generator and an electric poweramplifier, irradiating the displacement measurement point in thepiezoelectric/electrostrictive actuator 20 with a laser 113 output fromthe laser Doppler vibrometer 112, and inputting the vibration speedwaveform obtained of the piezoelectric/electrostrictive actuator 20 intothe waveform measurement analysis apparatus 114.

FIG. 12 is a configuration diagram showing a frequency characteristicmeasurement system for measuring the capacitance of apiezoelectric/electrostrictive actuator. As shown in FIG. 12, (forexample) the capacitance of the piezoelectric/electrostrictive actuator20 (see FIGS. 1 to 3) can be measured by a LCR meter 122. Specifically,the LCR meter 122 is electrically connected to thepiezoelectric/electrostrictive actuator 20 by means of a probe(measurement jig) to measure the capacitance and the loss; of thepiezoelectric/electrostrictive body 79 with applying a voltage betweenthe upper electrode 75 and the lower electrode 77. By combining thecapacitance, the loss, and the equivalent resistance (parallel, series)calculated from the capacitance and the loss, defects in the size(electrode area, thickness, electrode disconnection, etc.),polarization, insulation properties, output (displacement, sensitivity),and the like of the piezoelectric/electrostrictive device can bedetected. The capacitance and equivalent resistance may be used incombination with the resonance frequency characteristic value or may beused alone for judgment. The voltage and the frequency applied for thecapacitance and the loss are, for example, a frequency of 1 kHz and, forexample, a voltage of about 1V. The measurement conditions are respondedby using either the value where the circuit is regarded as a circuitwhere the capacity and the resistance are connected in parallel or thevalue where they are connected in series according to the kind of thedefect.

The apparatus for measuring the resonance frequency characteristicvalue, the displacement and the capacitance of the aforementionedpiezoelectric/electrostrictive actuator can be used for apiezoelectric/electrostrictive sensor.

Next, regarding a method and an apparatus for testing apiezoelectric/electrostrictive actuator of the present invention, aspecific method for estimating the displacement will be described basedon the actual measurement data.

FIG. 13 is a graph showing an example of the frequency characteristicsof the piezoelectric/electrostrictive actuator 20 measured by the use ofan apparatus described above and shown in FIG. 10 and showing thefrequency characteristics of a conductance shown in the screen of anetwork analyzer. From the frequency characteristics shown in FIG. 13,the first order peak conductance value (G1) and resonance frequency (f1)are obtained. The conductance value (G1) corresponds with the peakheight of the resonance waveform of the resonance frequencycharacteristic value of the first order, and the resonance frequency(f1) corresponds with the first order (k=1) of the first order resonancefrequency.

By the aforementioned conductance value (G1) and the resonance frequency(f1), the estimated displacement standard value MV is given as thefollowing formula (11). The formula (11) is a formula obtained from theformula (2) with R1=G1 and k=3. Depending on whether the estimateddisplacement is in a certain range (quality control value) or not, it ispossible to test the quality of the piezoelectric/electrostrictiveactuator.Estimated displacement standard value MV=G1/f1³  (11)

FIG. 14 is a graph showing the relation between the measureddisplacement and the capacitance (value standardized by a lot averagevalue) as the sample A and sample B extracted from the same lot amongthe manufactured piezoelectric/electrostrictive actuators 20 as theobjects. In addition, FIG. 15 is a graph obtained by setting up thefirst order regression equation of the measured displacement and thecapacitance with the sample A and sample B as the objects withoutdistinction and showing the relation between the estimated displacementand the measured displacement. Incidentally, the sample A is a samplehaving a small position shift amount between the substrate 44 and thepiezoelectric/electrostrictive actuating portion 78 and a smallundulation of the vibration portion 66, and the sample B is a samplehaving a large position shift amount between the substrate 44 and thepiezoelectric/electrostrictive actuating portion 78 and a largeundulation of the vibration portion 66.

From the results shown in FIGS. 14 and 15, it is understood that, whenthe position shift between the substrate 44 and thepiezoelectric/electrostrictive actuating portion 78 and the undulationamount of the vibration portion 66 in the piezoelectric/electrostrictiveactuator 20 are changed, correlation between the displacement and thecapacity becomes poor to fail to estimate the displacement by thecapacitance.

FIG. 16 is a graph showing the relation of the displacement and theestimated displacement amount standard value MV (standardized by a lotaverage value) with the same sample A and sample B as the objects. FIG.17 is a graph obtained by setting up the first order regression equationof the measured displacement with the same sample A and sample B as theobjects without distinction and showing the relation between theestimated displacement and the measured displacement.

From the results shown in FIGS. 16 and 17, it is understood that, evenwhen the position shift between the substrate 44 and thepiezoelectric/electrostrictive actuating portion 78 and the undulationamount of the vibration portion 66 in the piezoelectric/electrostrictiveactuator 20 are changed, correlation between the displacement and theestimated displacement standard value MV is secured to be able toestimate the displacement with high precision.

Since a piezoelectric/electrostrictive actuator has conventionally beentested on the basis of only the capacitance of thepiezoelectric/electrostrictive body, the difference of the otherelements constituting the piezoelectric/electrostrictive actuator, thatis, the difference of the substrate and the like constituted of thevibration portion and the support portion among the products has notbeen reflected on the test result. Therefore, it had a limitation inimprovement of the precision of the test. However, in a method and anapparatus for testing a piezoelectric/electrostrictive actuator of thepresent invention, the test is performed on the basis of a resonancefrequency characteristic value obtained from the manufacturedpiezoelectric/electrostrictive actuator. Since all the elements(including unpredictable elements) constituting thepiezoelectric/electrostrictive actuator are reflected on the resonancefrequency characteristic value, the variance in the displacement can beidentified without fail, and the precision for the test is higher thanthat by a conventional means to be able to judge whether it is a goodproduct or not more precisely. Since the test is not accompanied by anydisassembly/breakage of a piezoelectric/electrostrictive actuator, thetest does not require much time. For example, a micro switch where agood piezoelectric/electrostrictive actuator which passed the test isused as the actuator portion has the displacement of the vibrationportion in a certain range and the suppressed variance of switchoperation.

A method and an apparatus for testing a piezoelectric/electrostrictiveactuator of the present invention have been described with showing anexample of a method for estimating a displacement. Since a method and anapparatus for testing a piezoelectric/electrostrictive sensor of thepresent invention is an invention in accordance with a method and anapparatus for testing a piezoelectric/electrostrictive actuator of thepresent invention, the description with referring to a drawing will beomitted.

An apparatus for testing a piezoelectric/electrostrictive actuator ofthe present invention and an apparatus for testing apiezoelectric/electrostrictive sensor can be manufactured by purchasinga commercial network analyzer or impedance analyzer, creating a program(software) for realizing the aforementioned means, and mount it on acomputer. The input required by an apparatus for testing apiezoelectric/electrostrictive actuator of the present invention and anapparatus for testing a piezoelectric/electrostrictive sensor of thepresent invention can be obtained by the network analyzer and theimpedance analyzer. The input is one or more frequency characteristicvalues selected from the group consisting of the heights and areas ofthe peaks of the resonance waveforms and the difference of the maximumand minimum of the first order or first to higher orders of theresonance frequency characteristic values and the k-th order (k=1 to 4)of the first or first to higher orders of resonance frequencies. By anapparatus for testing a piezoelectric/electrostrictive actuator of thepresent invention and an apparatus for testing apiezoelectric/electrostrictive sensor, a method for testing apiezoelectric/electrostrictive actuator of the present invention and amethod for testing a piezoelectric/electrostrictive sensor can beconducted.

Piezoelectric/electrostrictive devices (piezoelectric/electrostrictiveactuator and piezoelectric/electrostrictive sensor) which are thetargets of a method and an apparatus for testing apiezoelectric/electrostrictive device of the invention each shows a unithaving a comprehensive function by the use of strain induced by anelectric field or charge/electric field induced by stress and has apiezoelectric/electrostrictive body and at least a pair of electrodes asthe constituents, and it is not limited to a narrowly-definedpiezoelectric/electrostrictive device using an inverse piezoelectriceffect generating a strain amount almost proportional to the appliedelectric field, a piezoelectric effect generating an amount of chargeinduced by stress, or an electrostrictive effect generating a strainamount almost proportional to the square of the applied electric field,and there are included piezoelectric/electrostrictive devices each usesa phenomenon such as polarization inversion shown in the generalferroelectric material and phase transition between an antiferroelectricphase and a ferroelectric phase shown in an antiferroelectric material.In addition, whether a polarization treatment is performed or not issuitably determined on the basis of the characteristics of the materialused for the piezoelectric/electrostrictive body constituting apiezoelectric/electrostrictive device.

Next, an embodiment of a method for adjusting apiezoelectric/electrostrictive actuator of the present invention will bedescribed. In a method for adjusting a piezoelectric/electrostrictiveactuator of the present invention, the displacement of a plurality ofpiezoelectric/electrostrictive actuators is estimated by the use of theaforementioned method for testing a piezoelectric/electrostrictiveactuator of the present invention, and an upper electrode is trimmedwith regard to at least some of the plurality ofpiezoelectric/electrostrictive actuators on the basis of the estimateddisplacement of each piezoelectric/electrostrictive actuator to adjustthe displacement of the piezoelectric/electrostrictive actuatorsuniformly. Here, trimming means to remove an unnecessary portion and toremove a part of a specific portion of a piezoelectric/electrostrictiveactuator in order to adjust the displacement of thepiezoelectric/electrostrictive actuator.

Since the resonance frequency characteristic value R in the formula (1)is changed by trimming the upper electrode of thepiezoelectric/electrostrictive actuator, the displacement of thepiezoelectric/electrostrictive actuator can be adjusted. In addition, totrim the upper electrode of a piezoelectric/electrostrictive actuatormeans to change the conductance G1 in the formula (11).

When the upper electrode is trimmed, the aforementioned resonancefrequency characteristic value R (conductance G1) becomes small.Therefore, it is preferable that the displacement of a plurality ofpiezoelectric/electrostrictive actuators is estimated and that the upperelectrode is trimmed with regard to the piezoelectric/electrostrictiveactuator having the estimated displacement larger than the standardvalue of the displacement set in advance. In addition, it is preferablethat the relation between the displacement of thepiezoelectric/electrostrictive actuator to be changed and the trimmingamount of the upper electrode is measured in advance to prepare astandard curve and that the trimming amount is determined on the basisof the measurement result (standard curve).

The trimming method of the upper electrode of thepiezoelectric/electrostrictive actuator is preferably a processingmethod such as laser irradiation, electron beam irradiation, andcutting. Of these, the processing method by laser irradiation is morepreferable because a beam wave length can be selected in accordance withthe characteristics of the material to be removed. In laser irradiation,it is particularly preferable to use a YAG laser of the third or fourthorder. The wave length of the laser is close to the wave lengthabsorption band of gold (Au) capable of forming the upper electrode, itis easy to narrow down the beam, and depth of field is small. Therefore,even in the case of a thin upper electrode, trimming is possible withoutimparting a damage such as a crack on the piezoelectric/electrostrictivebody.

In addition, as shown in FIGS. 18A and 18B, it is preferable that thetrimming of the upper electrode 75 of the piezoelectric/electrostrictiveactuator 50 is performed by forming a circular through-hole 81 or a slit(slit in the upper electrode) 82 in the upper electrode 75. The circularthrough-hole 81 is a through-hole having a diameter of 10 to 50 μmformed in the upper electrode 75, and at least one through-hole isformed in accordance with the displacement to be adjusted. The circularthrough-hole 81 is preferably formed in the central portion of the upperelectrode 75 because the displacement is remarkably changed. The slit 82to be formed in the upper electrode 75 is a rectangular through-hole,and at least one slit is formed in accordance with the displacement tobe adjusted. Both the slit 82 and the circular through-hole 81 may beformed. The width of the slit 82 is preferably 10 to 50 μm. The slit ispreferably formed in the upper electrode in the case that moreremarkable change of the displacement of thepiezoelectric/electrostrictive actuator is desired. FIG. 18A is aschematic view showing a cross section including the vibration portionand the piezoelectric/electrostrictive actuating portion of apiezoelectric/electrostrictive actuator of the present inventionadjusted according to a method for adjusting apiezoelectric/electrostrictive actuator of the present invention. FIG.18B is a plan view schematically showing apiezoelectric/electrostrictive actuator of the present inventionaccording to the present invention adjusted by a method for adjusting apiezoelectric/electrostrictive actuator of the present invention.

Further, as in the piezoelectric/electrostrictive actuator 60 shown inFIG. 20, in the case that the trimming of the upper electrode 75 iscircular through-holes 81 and 84, it is preferable that thethrough-holes 81 and 84 have different diameters. In thepiezoelectric/electrostrictive actuator 70 shown in FIG. 21, in the casethat the trimming of the upper electrode 75 is circular through-holes 85and 86 likewise, the through-holes 85 and 86 have different diameters,which is a preferable embodiment.

In addition, as the piezoelectric/electrostrictive actuator 80 shown inFIG. 22, in the case that the trimming of the upper electrode 75 isslits 87 and 88, it is preferable that the slits 87 and 88 havedifferent widths. As the piezoelectric/electrostrictive actuator 90shown in FIG. 23, in the case that the trimming of the upper electrode75 is one slit 89, the width of the slit may be changed (different) insuch a manner that (for example) the end portions are wider.

A preferable position of trimming of a piezoelectric/electrostrictiveactuator (place to be trimmed) is the portion where the maximumdisplacement of the piezoelectric/electrostrictive actuator isgenerated. FIG. 19A is a graph showing a displacement in each positionin the longitudinal direction of a piezoelectric/electrostrictiveactuator. The longitudinal e direction means the direction shown in FIG.2 (direction of the A-A′ cross section in FIG. 1) in thepiezoelectric/electrostrictive actuator 20 shown in FIGS. 1 to 3. Inaddition, FIG. 19B is a graph showing a displacement in each position inthe short-side direction of a piezoelectric/electrostrictive actuator,and the direction is the direction shown in FIG. 3 (direction of theB-B′ cross section in FIG. 1) in the piezoelectric/electrostrictiveactuator 20 shown in FIGS. 1 to 3. As understandable from FIGS. 19A,19B, 2 and 3, in the piezoelectric/electrostrictive actuator 20, theportion where the maximum displacement is generated is the centralportion of the piezoelectric/electrostrictive actuator (with the cavityas the base), and the piezoelectric/electrostrictive actuators 50, 60,70, 80 and 90 shown in FIGS. 18A to 23 are trimmed in preferablepositions.

In addition, the preferable position of trimming of thepiezoelectric/electrostrictive actuator (place to be trimmed) is theportion having the maximum amplitude in the first order of the resonancemode. In the piezoelectric/electrostrictive actuator 20, the portionhaving the maximum amplitude of the resonance made of the first order isthe central portion of the piezoelectric/electrostrictive actuator (withthe cavity as the base), and the piezoelectric/electrostrictiveactuators 50, 60, 70, 80 and 90 shown in FIGS. 18A to 23 are trimmed inpreferable positions.

The plurality of piezoelectric/electrostrictive actuators where thedisplacement is adjusted by a method for adjusting apiezoelectric/electrostrictive actuator of the present invention may bepiezoelectric/electrostrictive actuators assembled on one substrate orpresent separately on different substrates.

In addition, it is also a preferable embodiment where the“piezoelectric/electrostrictive body” of each of at least part of theplurality of piezoelectric/electrostrictive actuators is trimmed on thebasis of the estimated displacement of each of thepiezoelectric/electrostrictive actuators to adjust the displacement ofthe plurality of piezoelectric/electrostrictive actuators uniformly.

When the piezoelectric/electrostrictive body is trimmed, the resonancefrequency f in the formula (1) becomes small. Therefore, it ispreferable that the displacement of the plurality ofpiezoelectric/electrostrictive actuators is estimated to subject thepiezoelectric/electrostrictive body of each of thepiezoelectric/electrostrictive actuators each having a displacementsmaller than the standard value of the preset displacement to trimming.In addition, it is preferable that the relation between the displacementto be changed of the piezoelectric/electrostrictive actuator and thetrimming amount of the piezoelectric/electrostrictive body is measuredin advance to prepare a standard curve and that the trimming amount isdetermined on the basis of the measurement result (standard curve).

The trimming method of the piezoelectric/electrostrictive body of thepiezoelectric/electrostrictive actuator is preferably a processingmethod such as laser irradiation, electron beam irradiation, andcutting. Of these, the processing method by laser irradiation is morepreferable because a beam wave length can be selected in accordance withthe characteristics of the material to be removed.

In addition, it is preferable that the trimming of thepiezoelectric/electrostrictive body of thepiezoelectric/electrostrictive actuator is performed by forming a slitin the piezoelectric/electrostrictive body. The slit formed in thepiezoelectric/electrostrictive body is a rectangular groove, and atleast one slit is formed in accordance with the displacement to beadjusted. The width of the slit is preferably 10 to 50 μm. The positionfor forming the slit is preferably an outer edge portion of thepiezoelectric/electrostrictive body.

In addition, it is also a preferable embodiment where both thepiezoelectric/electrostrictive body and the upper electrode of each ofat least part of the plurality of piezoelectric/electrostrictiveactuators are subjected to trimming. The piezoelectric/electrostrictiveactuator shown in FIGS. 18A and 18B is an example where both thepiezoelectric/electrostrictive body 79 and the upper electrode 75 weresubjected to trimming. The trimming of thepiezoelectric/electrostrictive body 79 was performed by forming the slit(slit of piezoelectric/electrostrictive body) 83.

Next, an embodiment of a piezoelectric/electrostrictive actuator of thepresent invention will be described. The piezoelectric/electrostrictiveactuators 50, 60, 70, 80 and 90 shown in FIGS. 18A to 23 were obtainedby adjusting the displacement uniformly by the use of a method foradjusting a piezoelectric/electrostrictive actuator of the presentinvention. Therefore, the piezoelectric/electrostrictive actuator 50,60, 70, 80 and 90 were obtained by adjusting the displacement uniformlyby the use of the aforementioned method for adjusting apiezoelectric/electrostrictive actuator of the present invention withregard to the piezoelectric/electrostrictive actuators before adjustmentmanufactured by the aforementioned method for manufacturing thepiezoelectric/electrostrictive actuator 20 (see FIGS. 1 to 3).

Since the piezoelectric/electrostrictive actuators 50, 60, 70, 80 and 90were obtained by adjusting the displacement uniformly by the use of theaforementioned method for adjusting a piezoelectric/electrostrictiveactuator of the present invention, the displacement is uniform as awhole.

In a method for adjusting a piezoelectric/electrostrictive sensor of thepresent invention, the piezoelectric/electrostrictive actuator isreplaced with a piezoelectric/electrostrictive sensor in theaforementioned method for adjusting a piezoelectric/electrostrictiveactuator of the present invention. In a method for adjusting apiezoelectric/electrostrictive sensor of the present invention, bytrimming a piezoelectric/electrostrictive sensor, the detectionsensitivity can be adjusted efficiently. In addition, since apiezoelectric/electrostrictive sensor of the present invention hasdetection sensitivity adjusted by a method for adjusting apiezoelectric/electrostrictive sensor of the present invention, thedetection sensitivity of a plurality of piezoelectric/electrostrictivesensors is adjusted uniformly.

EXAMPLE

Hereinbelow, the present invention will be described more specificallywith referring to Examples. However, the present invention is by nomeans limited by these Examples.

Example 1

There was manufactured, as a piezoelectric/electrostrictive actuatorbefore adjustment, a piezoelectric/electrostrictive actuator having thesame structure as that of the piezoelectric/electrostrictive actuator 20shown in FIGS. 1 to 3. The piezoelectric/electrostrictive actuatorbefore adjustment was manufactured by the following method. In the firstplace, a binder, a solvent, a dispersant, and a plasticizer were mixedwith zirconium oxide to prepare slurry. Next, the slurry was subjectedto a defoaming treatment to manufacture a green sheet having apredetermined thickness by a reverse roll coater method. Then, the greensheet was processed by laser processing into a predetermined shape.After a plurality of green sheets were piled up in sequence, a ceramicgreen laminate body was obtained by pressure bonding with heat. Thegreen sheet laminate body obtained was fired at a temperature of 1200 to1600° C. to obtain the substrate (corresponding with the substrate 44 ofFIGS. 2 and 3).

On one surface of the substrate, a piezoelectric/electrostrictiveactuating portion (corresponding with the piezoelectric/electrostrictiveactuating portion 78 of FIGS. 1 to 3) was formed. Specifically, thepiezoelectric/electrostrictive actuator before adjustment was obtainedby printing the lower electrode in a predetermined portion of onesurface of the substrate by screen printing, followed by firing at 1250to 1450° C., then printing a piezoelectric/electrostrictive body byscreen printing, followed by firing at 1100 to 1350° C., and thenprinting the upper electrode by screen printing, followed by firing 500to 900° C. to form a piezoelectric/electrostrictive actuating portion.Then, by the above method, two piezoelectric/electrostrictive actuatorsbefore adjustment was manufactured.

The piezoelectric/electrostrictive actuators before adjustment obtainedabove each had a thickness of the upper electrode of 0.5 μm, a thicknessof the piezoelectric/electrostrictive body of 13 μm, a thickness of thelower electrode of 3 μm, and a thickness of a vibration portion of 10 μm(see WO2004/013918).

Next, the displacement of two piezoelectric/electrostrictive actuatorsbefore adjustment obtained above was adjusted to obtain twopiezoelectric/electrostrictive actuators (Example 1). The adjustment ofthe displacement of the piezoelectric/electrostrictive actuators wasperformed by the following method. In the first place, the conductancevalue (G1) and the resonance frequency (f1) were obtained by the use ofa network analyzer (trade name: E-5100A, produced by AgilentTechnologies Japan Ltd.). Then, by the use of the aforementioned formula(11) (MV=G1/f1³), the estimated displacement standard value MV of eachof the piezoelectric/electrostrictive actuators before adjustment wasobtained. Next, by the use of the standard curve (standard curve of thetrimming amount) obtained by the method described below, the trimmingamount of the upper electrode of each of thepiezoelectric/electrostrictive actuators before adjustment wascalculated out, and the upper electrode of each of thepiezoelectric/electrostrictive actuators before adjustment was subjectedto trimming to adjust the displacement of the twopiezoelectric/electrostrictive actuators uniformly. The displacement ofthe two piezoelectric/electrostrictive actuators was adjusted in such amanner that the difference in the displacement between the twopiezoelectric/electrostrictive actuators is within 1% (±0.5%). Thetrimming of the upper electrode was performed by forming a plurality ofthrough-holes each having a diameter of 10 μm in the upper electrode bylaser irradiation. Next, the estimated displacement standard value MVwas obtained with regard to the piezoelectric/electrostrictive actuatorsafter trimming was performed. The results of comparison of thedisplacement (estimated displacement) of the twopiezoelectric/electrostrictive actuators between before trimming andafter trimming are shown in Table 1. In the Table 1, “before processing”shows the estimated displacement of 24 piezoelectric/electrostrictiveactuators before being subjected to trimming, and “after processing”shows the estimated displacement of two piezoelectric/electrostrictiveactuators after being subjected to trimming. In addition, the trimmingwas performed on the piezoelectric/electrostrictive actuator of the“actuator No. 2”.

TABLE 1 Displacement Displacement before after Actuator No. processingprocessing 1 1.00 1.00 2 1.05 1.01

[Standard curve of trimming] The standard curve (relation between theremoved area of the upper electrode and the change rate of the estimateddisplacement standard value MV) of the trimming amount was prepared bythe following method. In the first place, apiezoelectric/electrostrictive actuator having the same shape as thepiezoelectric/electrostrictive actuator before adjustment wasmanufactured, and the estimated displacement standard value of thepiezoelectric/electrostrictive actuator was measured. Then, the upperelectrode was subjected to trimming of a predetermined area, and theestimated displacement standard value of thepiezoelectric/electrostrictive actuator after trimming was measured.Then, the estimated displacement standard value of apiezoelectric/electrostrictive actuator was measured with increasing thetrimming area in stages to obtain the relation between the removed areaof the upper electrode and the estimated displacement standard valuechange rate. Here, the estimated displacement standard value change rateis a rate based on the estimated displacement standard value of thepiezoelectric/electrostrictive actuator in a state without trimming.Table 2 shows the relation between the estimated displacement standardvalue obtained above and the removed area of the upper electrode. FromTable 2, the relation of the removal area of the upper electrode and thechange rate of the estimated displacement standard value can be figuredout.

TABLE 2 Estimated Removed area of displacement standard upper electrodevalue of change rate 0.1% −1% 0.3% −2% 1.0% −4%

From Table 1, it can be understood that, by the aforementioned methodfor adjusting (the displacement of) the piezoelectric/electrostrictiveactuator, the difference of the displacement of thepiezoelectric/electrostrictive actuator was reduced to 1% after theadjustment (after trimming) to be uniformalized while it was 5% beforethe adjustment (before trimming).

INDUSTRIAL APPLICABILITY

A method and an apparatus for testing a piezoelectric/electrostrictiveactuator of the present invention can suitably be used as a means fortesting various piezoelectric/electrostrictive actuators applied to, forexample, a measurement equipment, an optical modulator, an opticalswitch, an electric switch, a micro relay, a micro valve, a conveyanceapparatus, an image display apparatus such as a display and a projector,an image drawing apparatus, a micro pump, a liquid drop dischargeapparatus, a micro mixer, a micro stirrer, and a micro reactor.Likewise, a method for adjusting a piezoelectric/electrostrictiveactuator of the present invention can suitably be used as a means foradjusting a displacement of various piezoelectric/electrostrictiveactuators.

In addition, a method and an apparatus for testing apiezoelectric/electrostrictive sensor of the present invention cansuitably be used as a means for testing variouspiezoelectric/electrostrictive sensors used for detecting fluidcharacteristics, sound pressure, micro weight, acceleration, or thelike. A method for adjusting a piezoelectric/electrostrictive sensor ofthe present invention can suitably be used as a means for adjustingdetection sensitivity of various piezoelectric/electrostrictive sensors.

1. A method for testing a piezoelectric/electrostrictive actuator, themethod including the steps of obtaining one or more frequencycharacteristic values of the piezoelectric/electrostrictive actuatorselected from the group consisting of heights and areas of the peaks ofresonance waveforms and a difference between a maximum and minimum valueof a first order or first to higher orders of the resonance frequencycharacteristic values of the piezoelectric/electrostrictive actuator andthe k-th order (k=1 to 4) of the first or first to higher orders ofresonance frequencies; and estimating a displacement of thepiezoelectric/electrostrictive actuator based on a relation between oneor more of the obtained frequency characteristic values; wherein thepiezoelectric/electrostrictive actuator comprises a support portion anda vibration portion, the vibration portion having apiezoelectric/electrostrictive actuating portion disposed thereon, andthe piezoelectric/electrostrictive actuating portion comprising at leastone piezoelectric/electrostrictive body sandwiched between at least twoelectrodes.
 2. The method for testing a piezoelectric/electrostrictiveactuator according to claim 1, wherein the relation is a relation ofdividing the one or more frequency characteristic values selected fromthe group consisting of the heights and areas of the peaks of theresonance waveforms and the difference of the maximum and minimum of thefirst order of the resonance frequency characteristic values of thepiezoelectric/electrostrictive actuator by the k-th order (k=1 to 4) ofthe first order of resonance frequency to estimate the displacement ofthe piezoelectric/electrostrictive actuator by the calculated valueobtained by the division.
 3. The method for testing apiezoelectric/electrostrictive actuator according to claim 1, whereinthe relation is a relation of dividing a sum of the one or morefrequency characteristic values selected from the group consisting ofthe heights and areas of the peaks of the resonance waveforms and thedifference of the maximum and minimum of the first to higher orders ofthe resonance frequency characteristic values of thepiezoelectric/electrostrictive actuator by the k-th order (k=1 to 4) ofthe first order of resonance frequency to estimate the displacement ofthe piezoelectric/electrostrictive actuator by the calculated valueobtained by the division.
 4. The method for testing apiezoelectric/electrostrictive actuator according to claim 1, whereinthe relation is a relation of dividing the one or more frequencycharacteristic values selected from the group consisting of the heightsand areas of the peaks of the resonance waveforms and the difference ofthe maximum and minimum of the resonance frequency characteristic valuefor each of the resonances of the first to higher orders of thepiezoelectric/electrostrictive actuator by the k-th order (k=1 to 4) ofresonance frequency and obtaining the sum of the values for each of theresonances to estimate the displacement of thepiezoelectric/electrostrictive actuator by the calculated value obtainedby the sum.
 5. The method for testing a piezoelectric/electrostrictiveactuator according to claim 2, wherein the displacement of thepiezoelectric/electrostrictive actuator is estimated by a value obtainedby further multiplying the calculated value by the capacitance of thepiezoelectric/electrostrictive actuator.
 6. A method for adjusting apiezoelectric/electrostrictive actuator comprising: estimatingdisplacements of a plurality of piezoelectric/electrostrictive actuatorsaccording to the method for testing a piezoelectric/electrostrictiveactuator of claim 1; and trimming the piezoelectric/electrostrictivebody of the piezoelectric/electrostrictive portion of at least some ofthe plurality of piezoelectric/electrostrictive actuators to uniformlyadjust the displacement of the piezoelectric/electrostrictive actuatorsuniformly.
 7. The method for adjusting a piezoelectric/electrostrictiveactuator according to claim 6, wherein both thepiezoelectric/electrostrictive body and the upper electrode of at leastsome of the plurality of piezoelectric/electrostrictive actuators aretrimmed.